🚀 DevNest

DevNest is a scalable backend platform inspired by X (Twitter), built with Node.js, TypeScript, NestJS, Prisma, PostgreSQL, and Redis.

It follows a modular architecture and focuses on building production-ready social platform features with performance, scalability, and maintainability in mind.

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🧠 Architecture Overview

DevNest follows the standard NestJS modular architecture using PostgreSQL as the single source of truth:

Module → Controller → Service → Repository (Prisma) → Database (PostgreSQL)

Why this architecture?

• ✅ Clear separation of concerns
• ✅ Single Source of Truth: PostgreSQL holds all critical user data (Users, Posts, Comments, Likes, Graph).
• ✅ Modular and scalable
• ✅ Dependency injection for better maintainability
• ✅ Pull-based Feed: The home feed is generated on-the-fly by querying posts from followed users, avoiding data duplication.

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📁 Project Structure

src/
├── auth/             # Authentication module
├── comments/         # Comments module
├── common/           # Shared utilities
├── email/            # Email module (Worker-compatible)
├── feed/             # Feed module
├── generated/        # Generated Prisma client code
├── lib/              # Library & helper functions
├── likes/            # Likes module
├── posts/            # Posts module
├── prisma/           # Prisma service
├── profile/          # User profile management
├── users/            # User management
├── app.module.ts     # Root module
├── main.ts           # Application entry point
├── worker.module.ts  # Worker entry module
└── worker.ts         # Worker entry point

prisma/
└── postgres/         # PostgreSQL schema & migrations
    └── schema.prisma

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🛠️ Tech Stack

• Node.js & TypeScript
• NestJS (Backend Framework)
• Node.js Clustering & Worker Threads (Horizontal scaling & async bcrypt operations via piscina)
• Prisma ORM (Database Access)
• PostgreSQL (Relational Database)
• Redis (Caching & Queues)
• BullMQ (Background Jobs & Queues)
• Authentication (JWT, Refresh Token Rotation, Google OAuth 2.0, Privacy Hashing)
• Testing & Performance (Jest for E2E, k6 for Load Testing)
• Code Quality (ESLint Flat Config & Prettier)
• Dockerization (Docker Compose for full environment)

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🛡️ Security & Privacy

DevNest implements advanced security and privacy features:

🔐 Authentication & Security

• Robust Token Generation: Refresh tokens include a unique UUID (tokenId) in the payload to prevent collisions during rapid authentication requests.
• Refresh Token Rotation: Each time a token is refreshed, a new one is issued, and the old one is revoked. Reuse of an old token triggers a chain revocation for security.
• Device Tracking: We log IP Address and User-Agent for each login to detect suspicious activity.
• IP Privacy: All IP addresses are hashed (SHA-256) before storage to protect user privacy.

🗑️ Data Management

• Soft Deletes: User accounts are soft-deleted (deletedAt timestamp). This action instantly revokes all active sessions (Refresh Tokens) and prevents further logins.
• Cascade Revocation: Deleting an account or detecting token reuse instantly invalidates all associated tokens.

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⚙️ Setup & Installation

📋 Prerequisites

• Node.js (v18+ recommended)
• Docker & Docker Compose (for easy database setup)
• Git

1️⃣ Clone the Repository

git clone https://github.com/johnvesslyalti/dev-nest.git
cd dev-nest

2️⃣ Configure Environment Variables

Create a .env file in the root directory (you can use .env.example as a template):

# PostgreSQL
POSTGRES_URL=postgresql://postgres:password123@localhost:5432/devnest?schema=public

# Redis
REDIS_URL=redis://localhost:6379

# Auth
ACCESS_SECRET=your_access_secret
REFRESH_SECRET=your_refresh_secret
PORT=3001

3️⃣ Start Infrastracture (Docker)

You can spin up the PostgreSQL and Redis instances utilizing the provided docker-compose.yml:

docker-compose up postgres redis -d

(Optionally, you can run the entire API inside Docker with docker-compose up -d)

4️⃣ Backend Setup

1. Install Dependencies

   npm install

2. Database Setup

   Generate the Prisma client:

   npm run generate

   Run migrations to set up the database schema:

   npm run migrate:pg

3. Start the Backend

   # Development mode
   npm run dev
   
   # Production mode
   npm run build
   npm run start:prod

   Server defaults to http://localhost:3001/api/v1.

4. Start the Background Worker (Optional but recommended) The worker handles background jobs such as sending emails.

   # Development mode
   npm run start:worker:dev
   
   # Production mode
   npm run build # (if not already built)
   npm run start:worker

🧪 Verifying the Backend

DevNest includes comprehensive tests.

1️⃣ Run E2E Tests (Jest)

Ensure your test databases are correctly configured, then run:

# Run all E2E tests
npm run test:e2e

# Run with coverage report
npm run test:e2e:cov

2️⃣ Manual API Verification

1. Ensure the backend is running (npm run dev).

2. Run the manual functional test:

   npm run test:manual

   Expected Output: ✅ All tests passed successfully!

3. Verify Authentication:

   npm run test:auth

🚀 Performance & Load Testing

DevNest is highly optimized to handle high concurrency and offload heavy CPU-bound tasks.

1. Worker Threads: bcrypt password hashing is entirely offloaded to a piscina worker pool.
2. Horizontal Scaling: The API leverages the Node.js cluster module to fork instances across cores.
3. Database Connection Pooling: Prisma connections are strictly regulated per-instance to prevent PostgreSQL connection exhaustion.

To run the load tests locally (ensure k6 is installed):

k6 run k6-scenario-test.js

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🧪 Development Principles

• ✅ Modules: Feature-based separation.
• ✅ DTOs: Strict input validation using class-validator.
• ✅ Guards: Role-based and auth-based access control.
• ✅ Prisma: Type-safe database queries.
• ✅ Prettier/ESLint: Consistent code style.
• ✅ Cursor Pagination: Keyset pagination implemented for efficient list rendering (e.g., Feed).

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👨‍💻 Author

Johnvessly Alti Backend-focused Software Engineer Building scalable systems with clean architecture.

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📄 License

MIT License